 (Credit: http://geologyindy.byu.edu/) |
The Smoky Mountains are part of the Blue Ridge Province of the south western limit of the 4000km Appalachian Mountain Range. They were formed in the Late Palaeozoic Variscan Orogeny (contemporaneous with the Arcadian Orogeny in America) following the closure of the Rheic Ocean and subsequent continental collision of Laurasia with Gondwana to form Pangea. They comprise metamorphosed sedimentary rocks between 1 billion and 350 million years in age. They have been folded, faulted and thrusted in several deformations caused by collisions between different terranes of crust as shown in the diagram.
The present topography is the result of millions of years of erosion exposing metamorphic basement and massive sandstone. Our holiday, in April 2009, was in the east Tennessee and west Carolina region in the Great Smoky National Park - the only free-access National Park in the States. A dominant feature in the locality is the Great Smoky Thrust Fault. |
| In the Park here are several locations known as 'coves'. They are areas of rich soil which the early settlers farmed for grazing and growing crops, mainly wheat. A good example is Cades Cove, shown below. | |
 Cades Cove panorama showing the fertile farmland surrounded by metamorphic overlying thrust beds |
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Geologically the coves are the upper beds of limestone/shale underlying the Great Smoky Thrust Fault. The overlying meta-sandstones and phyllite beds of the thrust have been eroded to expose the base of the thrust as shown in the diagram. (ref: Harry L Moore, 1988. A Roadside Guide to the Geology of the Great Smoky Mountains National Park, University of Tennessee, P137).
Originally, The Smokies got their name from the hazy blue aura form by water of respiration exuded from the indigenous forests. This is no longer the case; it has changed as a result of lumbering operations denuding the forests combined with atmospheric pollution, from vehicles and industry hundreds of miles from the Park, replacing the water vapour. |
 Cades Cove formation |
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We were fortunate to discover that our holiday coincided with the annual Great Smoky Mountain Spring Wildflower Pilgrimage. Folk travel from all over the States and Canada to see the bewildering array of wild flowers, so colourful and prolific in the Park in the Spring. Over 150 walks are arranged led by knowledgeable rangers, botanists, ecologists etc. I searched the programme for a geology walk and found only one that even mentioned the word, so I booked to join it. At the start of the walk the leader, in typical American fashion, asked us all to introduce ourselves, where we were from and what our interests were. I mentioned my interest in the geology and was hoping to learn something about it from the leader. After a while examining numerous trees, plants, flowers etc we came across an anomalous pile of rocks. The leader said "Well, Fred, what can you tell us about the geology then?" With a manageable piece of rock in hand, I spoke authoritatively about mountain building, metamorphism and schists, which they seemed to find interesting and satisfied their immediate curiosity.
Later I discovered that the anomalous pile of rocks was the fireplace/chimney of a long-since removed settler's log-cabin. When the Park was taken over by the State the settlers were forced to move out; they took the timbers but left behind the heavy stone parts - the chimney and fireplace. |
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 A typical settler's house chimney |
 A taper-grooved millstone |
| Of course, the early settlers needed to grind their wheat for flour so the areas' streams have many relict water mills of all conceivable designs. Naturally there was demand for grinding stones; they were either granite or sandstone. We came across the taper-grooved one on display shown in the photo. I couldn't help recalling the passion former MGA President, the late Tony Browne, had for the history, evolution and demise of millstones, especially those of Millstone Grit. He would have loved it here, as would anyone interested in geology, wildflowers and the history of the early settlers. | |
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For those seeking entertainment Dollywood (Dolly Parton's emporium) is nearby and, of course, some local bluegrass as shown in the photo.
Well worth an April holiday! Fred Owen June 2010 All the photos are Fred Owen's. Diagrams from the www and "A Roadside Guide to the Geology of the Great Smoky Mountains National Park" |
 Local entertainment |